OK, so I’m ashamed to admit that as a native speaker I think I’ve missed something somewhere. I was typing up some documentation and spellchecker kept bugging me. So I looked up some words and found this:

The suffixes ‑ance and ‑ence mean
“quality of” or “state of.” Words
ending in these suffixes are usually
nouns. There is no rule that governs
whether a word ends with
‑ance or ‑ence.

Even the dictionary on my Mac goes so far as to say:

ORIGIN from French ‑ence, from Latin
‑entia, ‑antia (from present participial stems ‑ent‑, ‑ant‑). Since
the 16th cent. many inconsistencies
have occurred in the use of ‑ence and
‑ance.

You shouldn't really be too surprised. (Natural) Language comes first, rules are imposed upon it long after. Only in artificial languages such as the programming ones are the rules and the language itself co-created.
– mickeyfJan 20 '11 at 16:23

@mickeyf, no, there are natural rules that people follow. Even ebonics has a pretty strict grammar structure, phrases such as "who dat?" are perfectly understandable to the people who speak and listen to it, even if they don't codify it as rules. Without any kind of rules (codified or not) communication wouldn't be possible.
– Stephen FurlaniJan 20 '11 at 16:25

2

@mickeyf: I guess you both need to agree on the definition of "rules". It sounds to me that mickeyf is talking about prescriptive rules, which are applied at some point in the middle of the life of a language, and you are talking about rules in the sense of structured grammar that all language speakers must necessarily have. I think what this really boils down to is that written language is a synthetic thing and rules for spelling can be inconsistent and even contradictory at times.
– KosmonautJan 20 '11 at 21:19

4 Answers
4

Yes, this is for real. No, there really is no rule. There used to be a rule in Latin, though. Etymonline explains in more detail:

-ancesuffix attached to verbs to form abstract nouns of process or fact (convergence from converge), or of state or quality (absence from absent); ultimately from L. -antia and -entia, which depended on the vowel in the stem word. As Old French evolved from Latin, these were leveled to -ance, but later French borrowings from Latin (some of them subsequently passed to English) used the appropriate Latin form of the ending, as did words borrowed by English directly from Latin (diligence, absence). English thus inherited a confused mass of words from French and further confused it since c.1500 by restoring -ence selectively in some forms of these words to conform with Latin. Thus dependant, but independence, etc.

+1 This process of borrowings was indeed even more chaotic than I already suspected.
– CerberusJan 20 '11 at 14:37

@RegDwight, serious comment: thanks for the answer. dependant shows up as misspelled though on Google and my Mac. Have these been changing back in recent years or something because I feel like my brain is rotting trying to figure all this stuff out. (writing code has borrowed too much of my language regions..)
– Stephen FurlaniJan 20 '11 at 14:43

3

@Stephen: as an adjective, dependant is the obsolete spelling of dependent. As a noun, it is dependant in the UK, but dependent in the US, where dependant would be considered a misspelling.
– RegDwigнt♦Jan 20 '11 at 14:54

There are four conjugations of verbs in Latin, verbs that end in -are, -ēre, -ere, and -ire. The four conjugations are still evident in Spanish, French, Italian, etc. In English nouns that derive from these verbs end with -antia, -entia, and -ientia, from which we eventually get our nouns ending with -ance, -ence, and -ience.

e.g. parlance is from parlare, insurgence is from insurgere, audience is from audire. So remembering the spelling in English helps if you studied Latin ;)

However, standard spelling in English wasn't a huge priority until people like Samuel Johnson started writing dictionaries, so there are all sorts of exceptions to these rules.

The following is meant to supplement not supplant existing answers. In general, you look at what it was in Latin; however, there are several prominent exceptions.

The Etymonline entry regarding this is cribbed and abbreviated from the OED. Here’s what the OED says about these.

‑ance and ‑ence

‑ance

a. Fr. ‑ance :– L. ‑ānt‑ia, ‑ēnt‑ia, ‑ent‑ia
(see ‑ence), all of which in words that survived into Fr., or were
formed in Fr. as nouns of action, on the pres. pple., were levelled under
‑ance. But other L. words of this form, subseq. adopted in Fr., took
‑ence or ‑ance, according to L. spelling. Thus of popular preservation
or formation, aidance, assistance, complaisance, nuisance,
parlance, séance; of later learned adoption from L., absence,
clémence, différence, diligence, providence, prudence, as well as
élégance, tempérance. Words of both classes were adopted in Eng. in
their actual Fr. forms, which they still generally retain. But, since 1500,
various words orig. in ‑ance from Fr. have been altered back to ‑ence,
after L.; and all words recently adopted from L., directly or through
mod.Fr., or formed on L. analogies, have taken ‑ence or ‑ance according
to the L. vowel. Hence, mod.E. words in ‑ance partly represent L.
‑āntia, but largely L. ‑entia, ‑ēntia, through OFr. ‑ance; partly
also mod.Fr. ‑ance from vbs. of various origin. On the other hand, OFr.
‑ance :– L. ‑entia, ‑ēntia, is, in consequence of refashioning,
partly represented by Eng. ‑ence. For the confusion and inconsistency
which this causes in current spelling, as in dependance, ‑dence,
resistance, subsistence, see ‑ence. As, in many cases, the OFr.
vbs. themselves, as well as their derivatives in ‑ance, were adopted in
Eng. (e.g. appear ‑ance, assist ‑ance, purvey ‑ance, suffer ‑ance),
the suffix became to a certain extent a living formative, and was occas.
used to form similar nouns of action on native vbs., as abid‑ance,
abear‑ance, forbear‑ance, further‑ance, hinder‑ance, ridd‑ance,
etc. For meaning, see ‑ence; and cf. ‑ancy.

‑ence

a. Fr. ‑ence, ad. L. ‑entia, forming abstr. sbs., usually of
quality, rarely of action, on ppl. stems in ‑ent‑, e.g. sapient‑em
knowing, sapient‑ia knowingness, sapience; audient‑em hearing,
audient‑ia the process of hearing, audience. As the ppl. stem had
‑ent‑, ‑ant‑, the derivative sbs. had ‑entia (prūdentia), ‑antia
(īnfantia); but all these were levelled in OFr. to ‑ance, in words that
survived in popular use, or were formed analogically on the pr. pple. in
‑ant; as aidance, assistance, complaisance, contenance,
nuisance, parlance, séance. These were sbs. of action or process, the
value with which the suffix was retained in Fr. as a living formative. But
subsequently other L. words in ‑ntia, which had not survived in the
living language, were readopted on the analogy of these, but with ‑ence
or ‑ance according to the L. vowel, e.g. absence, clémence,
diligence, élégance, présence, providence, prudence,
tempérance, violence. These were sbs. of quality or state; all Fr.
words in ‑ence are of this class. Both classes were adodpted in ME. in
their actual Fr. forms and senses, which they generally still retain; but
since 1500, some of those in ‑ance have been altered back to ‑ence
after L. All words since adopted from or formed on L., follow L. precedent
as to ‑ence or ‑ance. The result is that the modern spelling of
individual words, and still more of groups of cogn. words, is uncertain and
discordant; cf. assistance, consistence, existence, resistance,
subsistence; attendance, superintendence; ascendant, ‑ent,
‑ancy, ‑ency, condescendence; dependant, ‑ent, ‑ance, ‑ence,
independence; appearance, apparent; pertinence, appurtenance. In
sense, words in ‑nce are partly nouns of action, as in OFr., partly of
state or quality, as in L. The latter idea is more distinctly expressed by
the variant ‑ncy (see ‑y = ‑ie :– ‑ia) which has been formed in
Eng. as a direct adaptation of L. ‑ntia; see ‑ency, ‑ancy.

‑ant and ‑ent

‑ant

a. Fr. ‑ant, sometimes :– L. ‑entem, ‑āntem, ‑ēntem, ending of
pres. pple. (see ‑ent); sometimes a later adaptation of ‑āntem only.
All the participial forms were in OFr. levelled under ‑ant, the sole
ending of the pr. pple., as L. amānt‑, vidēnt‑, sedēnt‑,
crēdent‑em in Fr. amant, voyant, séant, croyant. But other words
were subsequently adopted in their L. stem form, as prudent, présent,
élégant. Hence Fr. words in ‑ant are of two kinds, one answering to L.
‑ānt, the other to L. ‑ent, ‑ēnt. All were adopted, in their actual
Fr. forms, in Eng., where they subseq. became ‑ˈau.nt; then again, with
the change of stress, ‑ant, as L. affīdent‑em, diffī‑dent‑em,
plicānt‑em, servient‑em, tenēnt‑em, OFr. afiant, defiant,
pliant, serjeant, tenant, ME. afiˈa(u).nt, defiˈa(u).nt,
pliˈa(u).nt, serjeˈau.nt, teˈnau.nt. Most of them retain ‑ant,
e.g. claimant, pleasant, poursuivant, servant, suppliant,
valiant; but since 1500 some have been refashioned with ‑ent after L.,
wholly (as apparaunt, ‑ent), or partly (as in pendant, ‑ent,
dependant, ‑ent, ascendant, ‑ent). Hence, inconsistency and
uncertainty in the present spelling of many words, in which L. and Fr.
analogies are at variance: see ‑ent. Many new words of this class have
been adopted from L. ‑āntem directly or through later Fr., or have been
formed on L. analogies, or adopted from mod.Fr. and Romance ‑ant,
‑ante; as concomitant, protestant, commandant, anæsthesiant. For
sense, see ‑ent.

‑ent

a. Fr. ‑ent, ad. L. ‑ent‑em, the ending of pr. pples. of vbs. of the
2nd, 3rd, and 4th conjugation, as rīdent‑em, currentem, audientem.
(In the pples. of the 3rd and 4th conjugation this ending represents OAryan
‑nt‑, or perh. ‑ent‑, of the ablaut‑series ‑ent‑, ‑ont‑, ‑nt‑;
cf. Skr. ‑ant‑, ‑at‑, Gr. ‑οντ‑, Goth. ‑and‑, OE. ‑end‑; in those
of the 2nd conjugation it represents this suffix combined with the thematic
‑e‑ of the vb.; similarly the ‑ant‑ of the 1st conjugation includes a
thematic ‑a‑.) In OFr. this suffix and the corresponding ‑ant‑em of the
1st conjugation were levelled under ‑ant, the sole ending of the Fr. pr.
pple., as riant, courant, mourant, levant ( :– L. levantem). At a
later time many L. forms in ‑ent‑, which had acquired an adj. sense,
were adopted in Fr. as adjs. with the ‑ent‑ unchanged, as diligent,
évident; some of these were duplicates of living ppl. forms in ‑ant, as
convénient = convenant, provident = pourvoyant, confident
= confiant. The Fr. words in ‑ant, ‑ent, which were adopted into
Eng., have generally retained the form of the suffix which they had in Fr.;
but since 1500 there has been a tendency to refashion them after Lat., and
hence several words in ‑ant have changed that ending for ‑ent, either
entirely or in certain senses. In mod.Eng. also many Lat. words in ‑entem
have been directly adopted, always in the form ‑ent. The conflict between
Eng. and Fr. analogies occasions frequent inconsistency and uncertainty in
the present spelling of words with this suffix; cf. e.g. assistant,
persistent; attendant, superintendent; dependant, ‑ent,
independent.

In sense the words in ‑ent, ‑ant are primarily adjs., sometimes
distinctly ppl., as convergent, obsolescent, errant, peccant; some,
however, are, like many words of the same type in Lat. and Fr., used as
sbs. (either in addition to the adj. use or exclusively), meaning (a) a
personal agent, as agent, claimant, president, regent; (b) a
material agent, as coefficient, current, ingredient, secant,
tangent, torrent; esp. in Medicine, as aperient, astringent,
emollient, expectorant.

Well, there seems to have some rules to that in English according to a blogger I've found on Oxford Dictionaries:

-ance or -ence?

These endings are used to make nouns, meaning either: a quality or
state (e.g. ignorance is the state of being ignorant about something)
or an action (e.g. emergence is the action of emerging from
somewhere).

One key way of knowing which ending to choose is to be aware of the
words that these nouns are formed from. Some are made from verbs (e.g.
performance from perform) and some are from adjectives (for example
intelligence from intelligent).

-ance

If the word is formed from a verb that ends in -y, -ure, or -ear, then
the ending of the noun will be spelled -ance, for example:

Verb: apply comply / Noun: appliance compliance

(...)

If the noun is related to a verb which ends in -ate, then the ending
is likely to be -ance, for instance:

Verb: deviate dominate / Noun: deviance dominance (...)

A further tip is that, if the stem of the word (the part before the
ending) ends in a ‘hard’ c (pronounced like the c in cab) or a ‘hard’
g (pronounced like the g in get), then the ending will be spelled
-ance. For example: significance; elegance.

As for the other nouns which end in -ance, there are no hard-and-fast
rules, so you may find it helpful to memorize them. Here’s a handy
list of the most common:

ABUNDANCE acceptance acquaintance

(...)

-ence

If the word is formed from a verb ending in -ere, then the ending will
be spelled -ence. For example:

Verb: adhere cohere / Noun: adherence coherence

(...)

So, you may ask, why is perseverance (from persevere) spelled -ance?
Sorry, it’s simply an exception to this rule…

Does the related verb end in a stressed -er syllable? If yes, then
-ence is the correct ending, as in:

Verb: confer infer / Noun: conference inference

(...)

Note that, although the verb differ is stressed on the first syllable
rather than the final –er, difference is still spelled with -ence at
the end. If the word contains the syllables -cid-, -fid-, -sid-, or
-vid- immediately before the ending, the correct suffix is -ence. For instance:

CONFIDENCE evidence

(...)

If the stem of the word ends in a soft c (pronounced like the c in
cell) or a soft g (pronounced like the g in gin), then the ending will
be -ence. For example:

ADOLESCENCE indulgence

(...)

Again, some words don’t follow these rules (or the ‘rules’ have
several exceptions, so can be rather difficult to learn). Here’s a
list of some common nouns ending in -ence:

Thank you for your interest in this question.
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